code: def test_reductions_axis_none_warning(op):
      df = cudf.DataFrame({"a": [1, 2, 3], "b": [10, 2, 3]})
      pdf = df.to_pandas()
      with pytest.warns(FutureWarning):
          actual = getattr(df, op)(axis=None)
      with expect_warning_if(
          op
          in {
              "kurt",
              "kurtosis",
              "skew",
              "min",
              "max",
              "mean",
              "median",
          },
          FutureWarning,
      ):
          expected = getattr(pdf, op)(axis=None)
  
      assert_eq(expected, actual, check_dtype=False)
  
imports: from decimal import Decimal
  from itertools import product
  import numpy
  import pandas
  import pytest
  import cudf
  from cudf import Series
  from cudf.core.dtypes import Decimal32Dtype, Decimal64Dtype, Decimal128Dtype
  from cudf.testing import _utils
  from cudf.testing._utils import NUMERIC_TYPES, assert_eq, expect_warning_if, gen_rand
label_desc: Use image node_id 19 for calling a global function with example usage: test_reductions_axis_none_warning(op) without return types